package org.ssmm2.common.plugins;
import java.util.Properties;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.SqlSource;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.plugin.Intercepts;
import org.apache.ibatis.plugin.Invocation;
import org.apache.ibatis.plugin.Plugin;
import org.apache.ibatis.plugin.Signature;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
import org.ssmm2.common.persistence.dialect.Dialect;
@Intercepts({ @Signature(type = Executor.class, method = "query", args = {
MappedStatement.class, Object.class, RowBounds.class,
ResultHandler.class }) })
public class PagingPlugin implements Interceptor {
private String dialectClass;
public void setDialectClass(String dialectClass) {
this.dialectClass = dialectClass;
}
final static int MAPPED_STATEMENT_INDEX = 0;
final static int PARAMETER_INDEX = 1;
final static int ROWBOUNDS_INDEX = 2;
final static int RESULT_HANDLER_INDEX = 3;
Dialect dialect;
public Object intercept(Invocation invocation) throws Throwable {
processIntercept(invocation.getArgs());
return invocation.proceed();
}
void processIntercept(final Object[] queryArgs) {
if(dialectClass!=null)
{
this.setDialect(dialectClass);
}
MappedStatement ms = (MappedStatement) queryArgs[MAPPED_STATEMENT_INDEX];
Object parameter = queryArgs[PARAMETER_INDEX];
final RowBounds rowBounds = (RowBounds) queryArgs[ROWBOUNDS_INDEX];
int offset = rowBounds.getOffset();
int limit = rowBounds.getLimit();
if (dialect.supportsLimit()
&& (offset != RowBounds.NO_ROW_OFFSET || limit != RowBounds.NO_ROW_LIMIT)) {
BoundSql boundSql = ms.getBoundSql(parameter);
String sql = boundSql.getSql().trim();
if (dialect.supportsLimitOffset()) {
sql = dialect.getLimitString(sql, offset, limit);
offset = RowBounds.NO_ROW_OFFSET;
} else {
sql = dialect.getLimitString(sql, 0, limit);
}
limit = RowBounds.NO_ROW_LIMIT;
queryArgs[ROWBOUNDS_INDEX] = new RowBounds(offset, limit);
BoundSql newBoundSql = new BoundSql(ms.getConfiguration(), sql,
boundSql.getParameterMappings(),
boundSql.getParameterObject());
MappedStatement newMs = copyFromMappedStatement(ms,
new BoundSqlSqlSource(newBoundSql));
queryArgs[MAPPED_STATEMENT_INDEX] = newMs;
}
}
private MappedStatement copyFromMappedStatement(MappedStatement ms,
SqlSource newSqlSource) {
MappedStatement.Builder builder = new MappedStatement.Builder(
ms.getConfiguration(), ms.getId(), newSqlSource,
ms.getSqlCommandType());
builder.resource(ms.getResource());
builder.fetchSize(ms.getFetchSize());
builder.statementType(ms.getStatementType());
builder.keyGenerator(ms.getKeyGenerator());
builder.keyProperty(ms.getKeyProperty());
builder.timeout(ms.getTimeout());
builder.parameterMap(ms.getParameterMap());
builder.resultMaps(ms.getResultMaps());
builder.cache(ms.getCache());
MappedStatement newMs = builder.build();
return newMs;
}
public Object plugin(Object target) {
return Plugin.wrap(target, this);
}
public static class BoundSqlSqlSource implements SqlSource {
BoundSql boundSql;
public BoundSqlSqlSource(BoundSql boundSql) {
this.boundSql = boundSql;
}
public BoundSql getBoundSql(Object parameterObject) {
return boundSql;
}
}
public void setProperties(Properties properties) {
if (dialectClass == null) {
dialectClass = properties.getProperty("dialectClass");
}
this.setDialect(dialectClass);
}
private void setDialect(String dialectClass)
{
try {
dialect = (Dialect) Class.forName(dialectClass).newInstance();
} catch (Exception e) {
throw new RuntimeException("cannot create dialect instance by dialectClass:"+ dialectClass, e);
}
System.out.println(PagingPlugin.class.getSimpleName() + ".dialect="+ dialectClass);
}
}